The production of Liquid Crystal Display (LCD) or Organic Light-Emitting Diode (OLED) display requires that the drive IC (Integrated Circuit) is made on a non-display area of the display panel through the bonding technology so as to input drive signals to the display panel.
In order to reduce the cost, the Gate Driver on Array (GOA) technique is used to integrate Thin Film Transistor (TFT) gate switching circuit into array substrate of the display panel to form the scan drive to the display, thereby saving the gate drive IC.
Using the OLED display as an example, in the process of display driving, the GOA circuit sends line scan drive signal to gate line of each row in turn to open TFT in pixels of each row; then data signal is transmitted to pixel electrode connected with the drain of TFT through the source of TFT via the data line, and the data signal is converted into the current that drives OLED to have a light-emitting display.
The GOA circuit comprises a plurality of cascade shift register, and an output of the shift register at each stage is connected with TFT gate in pixel units of each row. As the trend of the display panel with higher definition and higher PPI (Pixels Per Inc) develops and the pixel number of the display panel continuously grows, line number of the gate line required to be scanned by the shift register within a scanning time of a frame is increasing. However, each shift register includes a plurality of TFTs, which would cause loss of threshold voltage in the process of signal transmission. Therefore, in the process of line scanning, the above loss of the threshold voltage causes the pulse width of the scanning signal in each row to narrow, thereby reducing the driving capacity of the shift register.